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Short description.

The search is for pair-produced WIMPS, where the presence of the interaction is detected by the observation of an ISR photon and nothing else. At ILC (but not LHC) this kind of interaction can be described in a almost model-independent way with EFT. Apart from the obvious ee→nunu + ISR ireducible background, also ee→ ee (down the beam-pipe) + ISR are the backgrounds. No dedicated signal simulation is needed; one can simply reweight the ee→nunu + ISR gamma-spectrum (as a function of theta and E_gamma) to be that of any signal

This benchmark in particular can probe two features:

Photon detection and measurement.

Hermeticity, in particular the performance of the very forward calorimeters.

Main observables.

The main (and only) direct observables for the signal is the momentum of the ISR photon, The physics observable is the exclusion/discovery WIMPs in the mediator-mass/coupling plane for different lorentz-structures of the interaction.

Optimisation deliverables.

Gamma detection efficiency at all angles, in all relevant calorimeters.

Rejection power of the very forward calorimeters against other activity than the ISR.

IDR plots & note.

Photon reconstruction : The number of reconstructed photons per generated photon as a function of the signal photon energy.

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NrecNgenE_photon_IDR.pdf

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250

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NrecNgenE_photon_IDR.C

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250

Photon reconstruction : The number of reconstructed photons per generated photon as a function of cos_theta (left : plot only pfos identified as photon, right: plot all pfos passes cut criteria except for pid).

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NrecNgenCosTheta_photon_IDR.pdf

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250

View file

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NrecNgenCosTheta_photon_IDR.C

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250

View file

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NrecNgenCosTheta_allpfo_IDR.pdf

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250

View file

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NrecNgenCosTheta_allpfo_IDR.C

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250

Extra: Same as above but plot only |cos_theta|<0.7 and |cos_theta|>0.9 cases (outside of the drop at cos_theta=0.8). This indicates the drop at cos_theta=0.8 give no effect on Nrec/Ngen vs E.

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NrecNgenE_photon_IDR_wo_cosTheta08.pdf

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250

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NrecNgenE_photon_IDR_wo_cosTheta08.C

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250

BCal vetoing : Comparison between IDR-L and IDR-S models on the number of BCal clusters. The histograms are stacked. (500~fb$^{-1}$, no beam polarization). (.root files are uploaded because .C files do not reproduce the figures...)

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bcalveto_IDR-L.pdf

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250

View file

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bcalveto_IDR_L.C

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250

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bcalveto_IDR-S.pdf

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250

View file

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bcalveto_IDR_S.C

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250

Sensitivity : 95\% confidence level exclusion limits for different effective operators with a realistic sharing of the polarization at 4ab$^{-1}$ of H20 scenario; $(--,-+,+-,++)=(10\%,40\%,40\%,10\%)$.$\sqrt{s}=500$~GeV.

Update: Now Emax < 220GeV, which was introduced to avoid Z-return events, has been removed. (But still Emax<250 is set due to a technical issue in a macro.)